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Biomedical subjects

J M Walker

Publications and source records attributed to J M Walker.

At least 289 records · Page 16Linked to original sources
PubMed1979

The isolation, characterization and partial sequence of a peptide rich in glutamic acid and aspartic acid (HGA-2 peptide) from calf thymus non-histone chromosomal protein HMG 2. Comparison with a similar peptide (HGA-1 peptide) from calf thymus non-histone chromosomal protein HMG 1.

A 41-residue peptide (HGA-2) containing a continuous sequence of 35 glutamic and aspartic residues was isolated from non-histone chromosomal protein HMG 2. This highly acidic peptide is compared with a similar peptide (HGA-1) isolated from non-histone chromosomal protein HMG 1.

Amino Acid Sequence↗
PubMed1979

Malignant hypertension and cigarette smoking.

The smoking habits of 48 patients with malignant hypertension were compared with those of 92 consecutive patients with non-malignant hypertension. Thirty-three of the patients with malignant and 34 of the patients with non-malignant hypertension were smokers when first diagnosed. This difference was significant, and remained so when only men or black and white patients were considered separately. Results suggest that malignant hypertension is yet another disease related to cigarette smoking.

Female↗
PubMed1979

Flurazepam effects on sleep EEG. Visual, computer, and cycle analysis.

Analysis of sleep effects of flurazepam hydrochloride on four normal subjects confirmed that this drug substantially suppresses both REM and stage 4 sleep. Computer analysis disclosed that delta wave amplitude was greatly reduced by flurazepam. However, low density delta wave activity (ie, stage 2 sleep, which was increased in duration beyond the reduction in stage 4), permitted the number of delta waves and the time they occupied per night to remain at baseline levels. This finding suggests that sedative-hypnotics increase total sleep time by slowing the metabolic processes of sleep so that a longer sleep duration is required for the same biological effects. New observations on the induction times of REM and stage 4 effects are also presented. In general, the distortions in sleep EEG produced by flurazepam qualitatively resemble, but are quantitatively greater than, those produced by barbiturates in equivalent hypnotic doses.

Adult↗
PubMed1979

Extraction of small amounts of oxytocin from biological fluids by means of agarose-bound neurophysin.

The use of agarose-bound neurophysin for the extraction of oxytocin from biological fluids is described. Oxytocin can be extracted from plasma, urine and cerebrospinal fluid with a high rate of recovery and samples varying widely in volume and oxytocin concentration can be tested by the method. Columns can be used to extract and concentrate dilute samples, or to help identify small amounts of neurohypophysial hormones by affinity chromatography. The oxytocin can be eluted from the column directly into the buffer used for subsequent bioassay. The composition of the final extract is constant and independent of the composition of the sample. The specificity of the binding is high. It is suggested that the method has many advantages over others in current use.

Animals↗
PubMed1979

Mild hypertension: to treat or not to treat?

In the second half of this century, morbidity and mortality from cardiovascular disease has reached epidemic proportions. The major risk factor associated with cardiovascular disease has been found, from various epidemiological studies, to be elevated blood pressure. Therefore, a lot of energy has been expended in prospective therapeutic trials in attempting to detect whether treatment of high blood pressure is beneficial. In severe hypertension, where the risk to the individual is considerable, this benefit has been demonstrated with relative ease. However, it has not yet proven possible to show conclusive benefit of treatment in the mild group of hypertensives, which form the vast majority of patients seen in general practice. A different approach has been advocated where account is taken of other coincidental cardiovascular risk factors; their presence or absence should help the clinician decide whether to treat or not to treat in the individual case.

Aging↗
PubMed1978

Studies on the degradation of high mobility group non-histone chromosomal proteins.

During the isolation of high mobility group non-histone proteins from calf thymus chromatin by methods described previously (e.g. Goodwin, G.H., Nicolas, R.H. and Johns, E.W. (1975) Biochim. Biophys, Acta. 405, 280--291) protein degradation occurs resulting in a number of proteins appearing in the chromatin extracts which are not present in high mobility group protein preparations in which proteolysis has been completely inhibited. These extra proteins, formerly numbered high mobility group proteins 3, 5, 6 and 8, are thus probably degradation products of other nuclear proteins, produced during the isolation procedure. From the amino acid analyses, tryptic peptides and N-terminal sequences, it is concluded that high mobility group protein 3 is probably a degradation product of high mobility group protein 1. The amino acid analysis of high mobility group protein 8 is very similar to that of the N-terminal half of histone H1 suggesting that high mobility group protein 8 is a degradation product of this histone.

Amino Acids↗
PubMed1978

Isolation and partial sequence of the cyanogen bromide peptides from calf thymus non-histone chromosomal protein HMG 1.

Peptides produced by cyanogen bromide cleavage of non-histone chromosomal protein HMG 1 have been isolated and characterized, and their partial sequences determined. The sequence data presented here account for over half of the sequence of the HMG 1 molecule and, together with previously published results, provide interesting information on the charge distribution within the molecule.

Amino Acid Sequence↗
PubMed1978

Studies on the conformational properties of the high-mobility-group chromosomal protein HMG 17 and its interaction with DNA.

The conformation of the non-histone chromatin protein, HMG 17, has been studied using circular dichroism, infrared and nuclear magnetic resonance spectroscopies, and by small-angle scattering. The results show that in free solution this protein has little or no secondary or tertiary structure in contrast to the other high-mobility-group proteins, HMG 1 and 2, which exhibit highly ordered structures. Protein HMG 17 binds to calf thymus DNA in an ionic-dependent manner, precipitating the DNA at high protein/DNA ratio. The nuclear magnetic resonance data suggest that the principle DNA-binding segment of HMG 17 is that between about residues 15 and 40.

Animals↗